Flapjack is a young boy with tan skin and curly, blond hair. He has black eyes and he wears a light olive drab scarf, a white & red striped t-shirt, and blue pants. He also sports a white sailor cap.
Flapjack is an eccentric young boy with a passion for adventure. He is full of energy and loves making new friends. Flapjack is easily influenced by his inspiration K'nuckles, Flapjack gives him all the trust in his heart and follows K'nuckles' every word, without thinking much of it. Flapjack is very naive and oblivious to danger, thus he is easily caught up in perilous situations. Being so young, he can be easily taken advantage of due to his kindness and purity.
When Flapjack was just an infant, Bubbie found him out in the sea, in a floating bundle of seaweed. When she took a closer look at the child, she declared him her "little angel." Later on, a man in a boat passes by making flapjacks. Baby Flapjack likes the name, it being his first word, and Bubbie decides to name him "Flapjack." From then on, Bubbie raised Flapjack as her own, taking him with her to Stormalong Harbor.
Sometime later, a now older Flapjack and Bubbie were out at sea when they discovered a drowning K'nuckles. After saving the old sea captain, he began telling various tales of his adventures before he got lost. When K'nuckles told Flapjack of Candied Island, Flapjack became very enthusiastic and decided to become an adventurer like K'nuckles. He has stuck by K'nuckles side ever since.
According to Thurop Van Orman, Flapjack's creator, Flapjack is 7 years old.
He wears purple underwear, as shown in the episode "Jar She Blows!" However, he occasionally wears white underwear.
Flapjack has a knack for writing original lyrics and melodies for songs, and has a "beautiful singing voice." His songs have included a lullaby for K'nuckles, a friendship-themed song involving K'nuckles, a musical tribute to a little old lady, and about 366 more unknown songs.
Flapjack was originally going to be voiced by actor/comedian Paul Reubens, but Reubens was unable to voice him at the time, so Thurop Van Orman decided to voice Flapjack himself.
Flapjack is a playable character in Cartoon Network's game, TKO. One of Flapjack's moves is called, "Hey, Bubbie" and when used, Flapjack launches Bubbie at the enemy. Peculiarly, Bubbie is very small in comparison to Flapjack.
Flapjack has been shown to have been a sailor multiple times in the series. In "N is for Navy" he was said to have been their best recruit. In "All Hands on Deck" he pretended to be a sailor in order to impress the "real" sailors.
Flapjack is briefly mentioned at the end of the Steven Universe episode "Say Uncle."